Renewable thermounit



NOV. 29, 1932. J, '5 RENEWABLE THERMOUNIT Filed July 6, 1931 7 Invenlor aye 2Z2 0152 2591? Patented Nov. 29, 1932 JOSEPH O'BRIEN, OF BALTIMORE, MARYLAND RENEWABLE THERMOUNIT Application filed July 6, 1931. Serial No. 549,055.

This invention has reference to a means for controllmg an electrical circuit, and the pm- 1 mary object of this invention is to provide a thermal unit adapted to be arranged to operate on electrical wiring systems for the protection against overloads and short circuits.

A still further object of the invention is to provide a renewable thermal-unit capable of such arrangement and so calibrated so that when placed in a wiring system an overload or short circuit will cause the thermal element of the unit to heat, resulting in an expansion of the thermal element, subsequently resulting in an open or dead circuit.

A still further object of the invention is to provide a unit of the above mentioned character equipped with manual resetting means for closing the circuit without disturbing or effecting a removal of the unit.

A still further object of the invention is to provide a fuse plug of the character above mentioned wherein the thermal unit may be used over an indefinite period of time, thus permitting a closing of the circuit without requiring replacement of the thermal element.

A still further object of the invention is to provide a circuit control device of the above mentioned character which may be placed in any standard fuse block where fuse plugs are now employed.

Other objects and advantages of the invention will be best understood from a study of the following description, taken in connection with the accompanying drawing where- 1n:

Figure 1 is an elevational view of the devlce.

Figure 2 is a top plan view thereof.

' Figure 3 is a vertical sectional elevational view therethrough.

Figure 4 is a top plan view of the device, the cover cap being removed.

Figure 5 is an elevational view of a base and thermo element carried thereby.

Figure 6 is a top plan view of the structure shown in Figure 5.

Figure 7 is a fragmentary detail sectional elevational view illustrating the manner of connecting one end of a coil spring to a free end of a pivot pin.

Referring in detail to the drawing, it will be seen that the unit is in the nature of a fuse plug, including a shell like body 10 of insulating material, and having an axial opening extending therethrough. A base 11 of insulating material closes one end of the body 10, and is secured in place through the medium of a metallic band or sleeve 12 that has threaded connection with one end of the body 10, and is also suitably formed for threaded connection with the socket of a fuse block or the like. One end of the sleeve12 is provided with an inwardly directed circular flange 12a suitably engaging the marginal edge portion of the base member 11 for retaining the latter in position.

The base member 11 is equipped with a suitable contact 13, and to the inner end of the contact 13 there is suitably connected one end of a thermal element or metal 14. The thermal element 14 is suitably shaped so that the free end thereof is parallel to the axis of the body and, upon heating and subsequent expansion of the element, said free end will be moved to the position suggested by broken lines in Figure 3.

A spring contact member 15 is suitably bent intermediate its ends and has said intermediate portion passed through a lateral opening in the wall of the shell 10, so that the outer end of the contact member 15 is clamped between the body 10 and the sleeve 12 as shown in Figure 3. The inner end of the contact member 15 extends upwardly into the bore of the body 10 and has bearing engagement with an adjacent end of a pivoted arm 16.

Arm 16 is formed integral with or otherwise secured to a transverse pivot pin 17, the ends of which are j ournalled in suitable notches formed in opposed walls of a noncircular end portion 18 of the body 10. The arm 16 is formed of metal or other suitable conductive material and its free end normally engaging the free end of the thermal-element 14 as shown in full line in Figure 3 thus completing the circuit. 1

Arm 16 is normally engaged with the free 10c end of the thermal element 14 through the medium of a spring 19 connected at one end to an apertured lu 17a on one end of the p'vot pin 17. At its other end, spring 19 18 connected to one end 20a ofan anchoring member 20 formed of metal. The member 20 has the end portion 20a thereof laterally engaging the non-circular end portion 18 of the ody and bent about one corner of the portion 18. The free end of the anchor (said anchor 20 being substantiall L-sha-pe) is clamped between the body 20 an the sleeve 12. (See Figure 3.) The body 10 together with the non-circular portion 18 thereof is suitably grooved for accommodating the anchor 20. Q v i For the outer end of the body 10 there is provided a'suitable cap 21 of non-conductive material and which fits snugly over the body 1 10. The skirt of the cap 21 is provided with a suitable notch through which extends the free end of the pivot pin 17, and on said end of the pin 17 is a suitable actuating knob 22. As clearly shown in Figures 1 and 2, the "knob 22 may be equipped with a suitable pointer adapted to be read against suitable indicia on the crown and skirt portions of the cap as for example as shown in Figure 1, the skirt portion adjacent the notch thereof is equipped with the word fOfl? so that when the arrow or pointer is turned to a position to be read against this word, the circuit is broken. That is tosay, due to an overload or for other reasons, arm 16 is out of engagement with thermal element 14 and is in the dotted line position shown in Figure 3. On the crown of the cap and suitably located, is the word On so that when the pointer is in the position shown in Figure 1, it will be apparent that the circuit is complete, and

tions and improvements coming within the scope of the appended claim.

Having thus described my invention, what I claim as new is:

A fuse plug comprising a body of insulating materlal having an opening therethrough, a base member closing one end of the opening, a metallic slee've threadedly connected with the body and having a circular flange engaged with the base member for holding the base member in position, a spring contact having one end clamped between the sleeve and body, and a free end extending into the opening, a contact member mounted on the base, a thermal member located in the body and having one end connected to the contact member on the base, a pivot pin traversing the opening in the body, an arm carried thereby, the free end of the spring contact extending between the pivot pin and a wall of the body for engaging the pivot pin of the arm, spring means urging the pin to rotate in one direction, to hold said arm against the free end of the thermal member, an exterior actuating knob on one end of the pin, and a cap fitted on the body closing the remaining end of the opening, said cap and said knob provided with cooperating means for visually indicating the conditions of the circuit.

In testimony whereof I aflix my signature.

' JOSEPH QBRIEN.

the parts are in the position shown in full 1 lines in Figure 3.

As shown in Figure 2, a portion of the cap adjacent the knob 22 is flattened so as not to u-interfere with rotation of the knob.

The operation and use of the device is thought apparent from the foregoing; the sleeve equipped end of the body is threaded into a fuse block or the like and normally arm 16 is engaged with thermal element 14. In the event of an overload or short circuit, thermal element 14 will expand thus moving out of engagement with arm 16, whereby thermal element 14 and arm 16 will assume the dotted line positions of Figure 3 thus break ng the circuit, this condition being sultably indicated by the means referred to in detail. To reset the device, that is, close the circuit, 'knob 22 is rotated in an anticlockwise direction for effecting engagement of arm 16 and thermal element 1 1.

Even though I have herein shown and described the preferred embodiment of the inventlon, it is to be understood that the same 1S susceptible of further changes, modifica-= 

